A liquid crystal display (LCD) panel is the primary component in a LCD device. A typical process for manufacturing an LCD panel basically includes providing two glass substrates, applying sealant to the glass substrates, and injecting liquid crystal molecules into a space between the glass substrates. The manufacturing process also includes forming an array of pixel electrodes on one of the glass substrates. The pixel electrodes are for controlling rotation of the liquid crystal molecules in operation of the LCD panel. The manufacturing process further includes forming color filter films on the other glass substrate. The color filter films enable the LCD panel to display colorful images in operation.
Referring to FIG. 8, a typical LCD panel 1 includes a thin film transistor (TFT) substrate 11, a color filter (CF) substrate 13, a liquid crystal (LC) layer 15, and a frame sealant 17. The TFT substrate 11 and the CF substrate 13 are spaced apart from each other a certain distance. The LC layer 15 is filled in the space between the TFT substrate 11 and the CF substrate 13, and is surrounded and encapsulated by the frame sealant 17 between the TFT substrate 11 and the CF substrate 13.
Referring to FIG. 9, the TFT substrate 11 is formed with a plurality of first patterned conductive layers 111 and a plurality of mark regions 113. The first patterned conductive layer 111 includes a plurality of conductive wires, and faces the LC layer 15. The mark regions 113 include block-shaped conductive layers, and are located at periphery portions of the TFT substrate 11.
The LCD panel 1 is manufactured by the so-called one drop fill (ODF) method, which is implemented according to the following steps. Firstly, the frame sealant 17 is applied to a periphery of the TFT substrate 11 so as to create a semi-closed space surrounded by the frame sealant 17. Secondly, drops of liquid crystal molecules are dripped into the semi-closed space to form the LC layer 15. Thirdly, the CF substrate 13 is attached to the TFT substrate 11. The frame sealant 17 is cured in a vacuum environment so that the TFT substrate 11 and the CF substrate 13 are firmly bonded together.
Since the attachment of the CF substrate 13 to the TFT substrate 11 is achieved using the frame sealant 17, the correct distance between the CF substrate 13 and the TFT substrate 11 depends at least in part on the precision with which the frame sealant 17 is applied to the TFT substrate 11. In other words, the frame sealant 17 needs to be applied on the TFT substrate 11 with a precise line width. Thereby, a uniform distance between the CF substrate 13 and the TFT substrate 11 can be obtained. As a result, the LCD panel 1 can provide good display performance.
As detailed above, control of the line width of the frame sealant 17 in the process of assembling the LCD panel 1 is critical to the final product quality. If the line width is too thin, liquid crystal molecules are liable to leak out from the LC layer 15. This in turn is liable to cause non-uniformity of the distance between the two substrates 11, 13 of the LCD panel 1. On the other hand, if the line width is too thick, line width would bring difficulties in the afterward cutting process and therefore affect the quality of product or would cause the LC layer 15 to be polluted by the frame sealant 17 due to the position of the frame sealant 17 being too close to the display area.
In the above-described conventional technique, the frame sealant 17 is applied directly onto the mark regions 113 formed on the TFT substrate 11. The exactness of the line width of the frame sealant 17 is basically determined by the precision of the equipment used to apply the frame sealant 17. Thus, it is common for precision deviation and unevenness of line width to occur.